Caltech's Engineering and Science magazine

Spring 2016

Moving to a new country on a new continent was a familiar feeling for Pradeep Ramesh(BS ’11). After spending his early childhood in India, he and his family moved to Singapore, where they lived for five years before moving to the United States when Ramesh was 12. So after finishing his bachelor’s degree in applied physics in 2011, it seemed natural to keep exploring the world.

Luckily for him, upon graduation Ramesh was awarded a Fulbright Fellowship to live and study in Denmark, studying biophysics at the Niels Bohr Institute in Copenhagen. At the time he began the fellowship, he had been a U.S. citizen for just under three years.

“I was totally surprised when I got to Denmark, because suddenly I was ‘The American’” Ramesh says. “I didn’t really even think of myself as an American until recently. And suddenly here I was in Denmark—a country of five million people, 90 percent of whom are ethnically Danish—and there was some sort of expectation that I represent and ‘defend’ my country’s ideology and policies.”

Adding to that pressure, each year the Fulbright committee selects one student studying in each participating European Union country and brings them to Brussels, the capital of the EU, for a week of visiting parliament and NATO headquarters—and Ramesh was selected as the Denmark representative, a task that included conversations with EU justices, members of parliament, and ambassadors.

“I felt very lucky to be selected,” he says. “You meet some very high profile political figures. And here we were, talking to them face to face, off the record, and they really opened up. They’re not just political ‘figures’—they’re other human beings.”

One particular experience stuck with Ramesh. “We were having dinner with the commanding general of NATO, around the time that the military campaign against Libyan leader Qaddafi began,” he remembers.“The general said that one of the biggest challenges was the unit system—American fighter pilots would report the target distance in miles, and here are the British and French and Danish who are actively flying planes and trying to quickly do conversions to meters. It was so funny. We’re on the same side but we can’t seem to come to agreement on something like units or language.

“I got to learn about the nuances of diplomacy, the complicated times when there really is no right or wrong answer—it kind of banishes that subconscious idea you might have that ‘America is always right,’” he says.

When not meeting with ambassadors or traveling throughout the EU, Ramesh did have a job to do—his Fulbright research straddled the intersection of physics and biology, examining the basic compartments of life: membranes. “All forms of life on Earth are compartmentalized,” he says. “You rarely get naked DNA or RNA just floating around. I wanted to better understand the physical forces that drive compartmentalization and affect the shape of lipid membranes, which form the boundaries of cells. How did these forces then shape the evolution of life on Earth?”

Though the fellowship is intended to provide a stipend for scientific research, another big takeaway, Ramesh says, was the global perspective he gained. “Cellular life may be compartmentalized, but there’s not such distinct delineations between science, culture, people, and policies,” he says. “Science is not a pure little bubble—you can’t separate it from cultural, political, and geographical contexts.”

Ramesh’s winding journey through the world has also been a winding journey through biology. After his work on membrane biophysics, he went on to graduate studies at UC Berkeley, where he wanted to model cancer dynamics using the principles of evolutionary game theory. While there, he met Mikhail Shapiro, with whom he moved back to Caltech—where Shapiro is now an assistant professor of chemical engineering—in order to start a new lab in molecular imaging. Ramesh is currently working to advance the nascent field of magnetogenetics by trying to engineer mammalian cells to be magnetic. This would allow researchers to control cellular function noninvasively using magnetic fields.

Rudolph A. Marcus (1923–)Nobel Prize in Chemistry in 1992 “for his contributions to the theory of electron transfer reactions in chemical systems”

Marcus, the John G. Kirkwood and Arthur A. Noyes Professor of Chemistry, discussed his post-Nobel experience in a recent interview.

“Life certainly became busier. I tried and did maintain the research program at the same rate as before in terms of number of people that were with me and in terms of doing things on my own. All along, I continued to do some thinking on my own; I just enjoy playing with ideas involving theory and trying to understand some experiments.

“In addition to having what I had before, then there were all these invitations that really arose primarily because of the Nobel Prize.

“But it meant for a far busier life, and doing new activities that took a lot of time made doing research on one’s own a little more difficult.

“There are various unanswered problems in fields that I’ve been involved with, including some that my group and I are working on currently, so I am excited to find the answers to those problems. For example, the field of ‘single molecule’ experiments has provided new challenges. In one study of a biological molecular motor, we have applied theories about how chemical and mechanical aspects within the system might work to data from single molecule experiments to build a more detailed model of the motors. To learn more, we are applying the same method to another type of single molecule experimental results on the same system.”

“The common theme is seeing something which is a puzzle and trying to find an answer to it. . . . It goes back to doing puzzles as a child, actually.”

David Baltimore (1938–)Nobel Prize in Physiology or Medicine in 1975 (with Renato Dulbecco and Howard Martin Temin) “for their discoveries concerning the interaction between tumour viruses and the genetic material of the cell”

Baltimore, the Robert Andrews Millikan Professor of Biology, and President Emeritus of Caltech, was interviewed recently about his life and work after the prize.

“When you win the Nobel Prize, you become much more visible as a member of the scientific community. Visible to the press, visible to your colleagues, visible to students. Today, and ever since, when I meet a student, I know that they’re looking at me and saying, ‘That’s a Nobel Prize winner.’ And it actually makes normal communication more difficult because they think I come from some other planet.

“I had to accept the medal of speaking for the scientific community and have spent now basically almost all of my career as a sort of visible member of the scientific community, conscious of a responsibility and an opportunity.

“I’ve been involved in some of the biggest changes in the nature of biology, the way we do it, and the controversies that have been associated with that. Probably the biggest one was the recombinant DNA controversy in 1975, partly as a result of my work. We suddenly realized that there was a new capability, the capability to cut and paste DNA and therefore to move genes from one organism to another, to modify genes, to capture genes, to use them in biotechnology, and that was a monumental new way of looking at biological experimentation and the capabilities of our profession. But it also raised the issue of whether we were going to create some kind of monster, some kind of problem, disease-causing organisms. And so the world got pretty worried about that.

“I was part of the organization that put together the Asilomar Conference, a conference that looked at this question of danger coming from the new capabilities and put in place a procedure whereby we could slowly extend the capabilities to new organisms and new ways of doing science with safe checks along the way so that this was done carefully over a decade. And I think that gave the general public a sense that we were being responsible as scientists.

“Inevitably the biggest impact that people will have seen from my career is the discovery of the reverse transcriptase because that won the Nobel Prize and stood out. I think that in all of the areas where I’ve worked, there are personal satisfactions which are as great as that— the success of my students.”

Robert H. Grubbs (1942–)Nobel Prize in Chemistry in 2005 (with Yves Chauvin and Richard R. Schrock) “for the development of the metathesis method in organic synthesis”

Grubbs, the Victor and Elizabeth Atkins Professor of Chemistry, talked about life after the Nobel in a recent interview.

“I really liked doing what I was doing before [the prize], so I’ve mostly continued doing that. I think my wife had the best statement on it. She said, ‘We now drink better wine and we dance more.’

“I’m getting old, so I’m going to have fun now. Part of what we’re doing is making better catalysts. . . . We’re also trying to define and find new transformations that use catalysts to convert a molecule, one into another one.

“There’s a new Hepatitis C treatment, and one of the molecules that is involved in that new treatment, which finally cures Hepatitis C, is a molecule made using our chemistry.

“And then another whole area which I’ve been working on for a long time, which is sort of my hobby now, is developing materials for biomedical applications.

“We probably have 10 different projects going now that are developing materials for really interesting [medical] applications. . . . It’s not biology; it’s what I call plumbing, and we’re having a good time developing these materials.

“The only thing going forward is that I hope we can have the opportunity to keep going for quite a while and these wonderful students keep showing up, and postdocs. I’d like to have a chance to do a few more things.”

Richard Feynman (1918–1988)Nobel Prize in Physics in 1965 (with Sin-Itiro Tomonaga and Julian Schwinger) “for their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles”

In January 2016, Caltech held an event celebrating the legacy of Richard Feynman, which included a long and revered teaching career both at the Institute and through a series of lectures aimed at laypeople interested in physics.

In a blog tribute titled “The Best Teacher I Never Had” and written for the event, Bill Gates remembers how he stumbled upon Feynman’s lectures.

“A friend and I were planning a trip together and wanted to mix a little learning in with our relaxation. We looked at a local university’s film collection, saw that they had one of his lectures on physics, and checked it out. We loved it so much that we ended up watching it twice. Feynman had this amazing knack for making physics clear and fun at the same time. I immediately went looking for more of his talks, and I’ve been a big fan ever since. Years later I bought the rights to those lectures and worked with Microsoft to get them posted online for free.

“In that sense, Feynman has a lot in common with all the amazing teachers I’ve met in schools across the country. You walk into their classroom and immediately feel the energy—the way they engage their students—and their passion for whatever subject they’re teaching.”

Mansi Kasliwal is a new assistant professor but certainly not a Caltech newbie. The astronomer earned her PhD here in 2011, having helped design and build the Palomar Transient Factory (PTF), an automated widefield survey at Palomar Observatory that systematically searches for cosmic transients—powerful events like supernovae that appear in the night sky with the light of a million to a billion suns, and then fade away.

“These are extreme events where a lot of elements that we see around us are actually synthesized,” says Kasliwal.

Kasliwal continues to work with PTF and its successor, the Zwicky Transient Facility (ZTF), but is also leading a major international project devoted to chasing and studying transients using observatories around the globe. Known as GROWTH, for Global Relay of Observatories Watching Transients Happen, the project was recently granted $4.5 million through the National Science Foundation’s Partnerships in International Research and Education (PIRE) program. Its goal is to detect transients and then “stay unbeaten by sunrise.”

“We just go around the globe and keep passing the baton so that the sky remains dark,” explains Kasliwal. Here are a few more fun facts about Kasliwal:

She grew up in Indore, India, and came to the United States as an adventurous15-year-old.

Noting Kasliwal’s love of the natural sciences, a teacher in India advised Kasliwal to apply to American boarding schools. She took her advice and attended a college-prep school in Connecticut for her junior year. She spent her senior year taking classes and working with a professor at Bryn Mawr College.

She studied applied and engineering physics as an undergrad at Cornell.

Astrophysics was only her concentration, but at Cornell she was able to work with the late Jim Houck, the principal investigator for the infrared spectrograph on NASA’s Spitzer Space Telescope. “Spitzer was being launched, and I got to see the data start flowing in,” says Kasliwal. “From then on, I was just completely hooked.”

Her work has already made it into textbooks.

Kasliwal received a freshman astronomy textbook in the mail from a professor she had interned with and was astonished to find a page in it dedicated to a supernova that she had discovered. “It was one of the most awesome moments for me,” she says.

In November 2015, Caltech marked both the 25th anniversary of the Beckman Institute and the 80th birthday of chemist Harry Gray with a two-day “Invention and Imagination in the Molecular Sciences” symposium. Gray and the late Arnold Beckman (PhD ’28), former Caltech professor and chairman emeritus of the Caltech board of trustees, began a close working relationship in the late 1960s, when Gray arrived at Caltech. Beckman (above, left) congratulates Harry Gray on becoming the first Arnold O. Beckman Professor of Chemistry in 1981. Gray is also the founding director of the Beckman Institute, a multidisciplinary center for research in the chemical and biological sciences that was dedicated in 1989 with funds from the Arnold and Mabel Beckman Foundation.

A new technique developed at Caltech that uses gas-filled microbubbles for focusing light inside tissue could one day provide doctors with a minimally invasive way of destroying tumors with lasers, and lead to improved diagnostic medical imaging.

The primary challenge with focusing light inside the body is that biological tissue is optically opaque. Unlike transparent glass, the cells and proteins that make up tissue scatter and absorb light. “Our tissues behave very much like dense fog as far as light is concerned,” says Changhuei Yang, professor of electrical engineering, bioengineering, and medical engineering. “Just like we cannot focus a car’s headlight through fog, scientists have always had difficulty focusing light through tissues.”

To get around this problem, Yang and his team turned to microbubbles, commonly used in medicine to enhance contrast in ultrasound imaging. First, gas-filled microbubbles encapsulated by thin protein shells and injected into tissue are ruptured with ultrasound waves. By measuring the difference in light transmission before and after such an event, the Caltech researchers can modify the wavefront of a laser beam so that it focuses on the original locations of the microbubbles. The result, Yang explains, “is as if you’re searching for someone in a dark field, and suddenly the person lets off a flare. For a brief moment, the person is illuminated and you can home in on their location.”

If the technique is shown to work effectively inside living tissue—without, for example, any negative effects from the bursting microbubbles—it could enable a range of research and medical applications. For example, by combining the microbubbles with an antibody probe engineered to seek out biomarkers associated with cancer, doctors could target and then destroy tumors deep inside the body or detect malignant growths much sooner.

“Ultrasound and X-ray techniques can only detect cancer after it forms a mass,” Yang says. “But with optical focusing, you could catch cancerous cells while they are undergoing biochemical changes but before they undergo morphological changes.”

Mars is blanketed by a mostly carbon dioxide atmosphere—one that is far too thin to prevent large amounts of water on the surface of the planet from subliming or evaporating. But many researchers have suggested that the planet was once shrouded in an atmosphere many times thicker than Earth’s. For decades that left the question, “Where did all the carbon go?”

Now scientists from Caltech and JPL think they have a possible answer. The team suggests that 3.8 billion years ago, Mars might have had only a moderately dense atmosphere. The researchers have identified a photochemical process that could have helped such an early atmosphere evolve into the current thin one without creating the problem of “missing” carbon.

“With this new mechanism, everything that we know about the martian atmosphere can now be pieced together into a consistent picture of its evolution,”says Renyu Hu, a postdoctoral scholar at JPL, a visitor in planetary science at Caltech, and lead author on the paper that appeared in Nature Communications.

When considering how the early atmosphere might have transitioned to its current state, there are two possible mechanisms for the removal of excess carbon dioxide (CO2). Either the CO2 was incorporated into minerals in rocks called carbonates or it was lost to space.

A separate study coauthored by Bethany Ehlmann, assistant professor of planetary science at Caltech, used data from several Mars-orbiting satellites to inventory carbonate rocks, showing that there are not enough carbonates in the upper crust to contain the missing carbon from a very thick early atmosphere.

To study the escape-to-space scenario, scientists examined the ratio of carbon-12 and carbon-13, two stable isotopes of the element carbon that have the same number of protons in their nuclei but different numbers of neutrons, and thus different masses. Comparing measurements from martian meteorites to those recently collected by NASA’s Curiosity rover, they found that the atmosphere is unusually enriched in carbon-13. To explain that, they describe a mechanism involving a photochemical cascade that produces carbon atoms that have enough energy to escape the atmosphere, and they show that carbon-12 is far more likely to escape than carbon-13.

“With this mechanism, we can describe an evolutionary scenario for Mars that makes sense of the apparent carbon budget, with no missing processes or reservoirs,” says Ehlmann, who is also a coauthor on the Hu study.

When certain massive stars use up all of their fuel and collapse onto their cores, explosions 10 to 100 times brighter than the average supernova occur. Astrophysicists from Caltech, UC Berkeley, the Albert Einstein Institute, and the Perimeter Institute for Theoretical Physics have used the National Science Foundation’s Blue Waters supercomputer to perform three-dimensional computer simulations to fill in an important missing piece of our understanding of what drives these blasts.

In the past, scientists have simulated the evolution of massive stars from their collapse to jet-driven explosions by factoring unrealistically large magnetic fields into their models—without explaining how they could be generated in the first place.

“That’s what we were trying to understand with this study,” says Luke Roberts, a NASA Einstein Fellow at Caltech and a coauthor on a paper reporting the team’s findings in the journal Nature. “How can you start with the magnetic field you might expect in a massive star that is about to collapse—or at least an initial magnetic field that is much weaker than the field required to power these explosions—and build it up to the strength that you need to collimate a jet and drive a jet-driven supernova?”

For more than 20 years, theory has suggested that the magnetic field of the innermost regions of a massive star that has collapsed, also known as a proto-neutron star, could be amplified by an instability in the flow of its plasma if the core is rapidly rotating, causing its outer edge to rotate faster than its center. However, no previous models could prove this process could strengthen a magnetic field to the extent needed to collimate a jet, largely because these simulations lacked the resolution to resolve where the flow becomes unstable.

Lead author on the paper Philipp Mösta—who started the work while a postdoctoral scholar at Caltech and is now a NASA Einstein Fellow at UC Berkeley—and his colleagues developed a simulation of a rapidly rotating collapsed stellar core and scaled it so that it could run on the Blue Waters supercomputer, known for its ability to provide sustained high-performance computing for problems that produce large amounts of information. The team’s highest-resolution simulation took 18 days of around-the-clock computing by about 130,000 computer processors to simulate just 10 milliseconds of the core’s evolution.

In the end, the researchers were able to simulate the so-called magnetorotational instability responsible for the amplification of the magnetic field. As theory predicted, they saw that the instability creates small patches of an intense magnetic field distributed throughout the core of the collapsed star. They found that a dynamo process connects those patches and generates currents that amplify the magnetic fields, turning them into the kind needed to power jets.

These glowing crystals generated by Tania Darnton, a Caltech graduate student in the lab of chemist Harry Gray, are composed of the tetraphenylphosphonium (Ph4P+) salt of the compound tetrakis(diphosphonato) diplatinate(II), commonly known as Pt(POP) due to its phosphorus-oxygenphosphorus bridges. This compound is a precursor to another molecule Darnton is studying for her thesis, which is a highly luminescent derivative of Pt(POP) with possible applications in oxygen sensing thin films and catalytic electron-transfer reactions. According to Darnton, the crystals were created via the slow evaporation of a methanol solution of the compound—quite by accident, in fact. She hadn’t synthesized the Ph4P+ salt before, and after several frustrating hours of trying unsuccessfully to isolate the compound she decided to just leave the solution out and try again in the morning. When she returned the following day, she was greeted with bright green crystals, which she called a “wonderful reward” after the disappointment of the night before. Such compounds could be used in building detectors for laboratories to ensure proper atmospheric conditions for sensitive chemical reactions.

The public high school in Blue Springs, Missouri, just outside Kansas City, graduates more than 500 seniors each year. Remarkably, the valedictorian in 2015 was the younger sister of the valedictorian in 2014—who was the younger sister of the valedictorian in 2013.

And all three are now Caltech undergraduates. These are the Butkovich sisters: junior Slava and sophomore Nina, both majoring in chemical engineering, and freshman Lazarina (“Laza”), currently deciding between chemical engineering and chemistry.

The sisters represent “a three-peat,” says Caltech admissions director Jarrid Whitney, not a package deal. “All our applicants are reviewed independently and without regard to siblings, parents, or other legacies. For three family members to receive consecutive offers of admission indicates how tremendously talented all three of them must be.”

For their part, Slava, Nina, and Laza (pictured right to left, below) find their own nearly identical trajectories unsurprising. “We were taught at a young age that science majors can do a lot of good for society,” Slava says.

In fact, according to all three, one of the biggest challenges since leaving high school has been learning to rely on something they had honestly never needed before now: study groups.